hey guys thanks for the replies, sorry took so long to get back, been a crazy week, been so busy starting a new job and trying to juggle things outside work. Was letting the bike tick over in the garage tonight. Not sure if it is my imagination but it seems to be knocking at its worse when it has a cold start, when the bike is warmed i can't hear it as much. I tried to pin point the sound, but not 100%, i believe it is coming from somewhere in the top half of the engine (im not that mechanical when it comes to the engine of a bike so couldn't think exactly where). As when it comes to not having a clue about engines, I think i might be best getting it checked by a mechanic? Like to try things myself, but have limited knowledge. Bike has 26k miles and its a 2001 b6.